ubuntu rosdep init或rosdep update失败

1、换热点，换wifi，多试试

2、sudo rosdep init失败
手动：在/etc/ros/rosdep/sources.list.d目录下新建一个文件，名20-defau.list，然后将https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.list中的内容复制进去。

20-default.list这个文件的内容如下：

# os-specific listings first
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx

# generic
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml
gbpdistro https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml fuerte

# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead

3、执行rosdep update失败
从下面github中直接下载，放到到/etc/ros/rosdistro目录下，rosdistro需要新建

git clone https://github.com/Jiangjianyu/ros-use.git

修改20-default.list脚本

# os-specific listings first
#yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx
yaml file:///etc/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx
 
# generic
#yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml
#yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml
#yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml
#gbpdistro https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml fuerte
 
yaml file:///etc/ros/rosdistro/master/rosdep/base.yaml
yaml file:///etc/ros/rosdistro/master/rosdep/python.yaml
yaml file:///etc/ros/rosdistro/master/rosdep/ruby.yaml
gbpdistro file:///etc/ros/rosdistro/master/releases/fuerte.yaml fuerte
 
# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead

退出保存后，执行rosdep update。在更新过程中，还有部分配置信息会从raw.githubusercontent.com上下载，但是反复几次，基本上就可以成功了。
经过上面两步，还是失败，请继续往下看。
sudo 打开/usr/lib/python2.7/dist-packages/rosdistro/下的__init__.py这个文件，按照下面的代码进行修改。

sudo gedit /usr/lib/python2.7/dist-packages/rosdistro/__init__.py
# 修改下边行
# index information
# DEFAULT_INDEX_URL = 'https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml'
DEFAULT_INDEX_URL = 'file:///etc/ros/rosdistro/master/index-v4.yaml'

保存后，执行

sudo apt-get update
rosdep update。

祝你成功！！！